T. Ryan

From Doom Wiki

T. Ryan is a Delta Labs scientist in Doom 3 whom the player meets on the monorail tram. During the demon invasion, Ryan's partner went to investigate but never returned and was likely killed by the demons. When the player meets Ryan, he is confused and scared and tells the player that Delta Labs is not safe and that the artefacts at Site 3 have something to do with the invasion. The player leaves Ryan on the Monorail tram to unlock the Delta Labs entrance. When the player returns to the Monorail, Ryan's body has been torn apart by several trites and a Commando.

T. Ryan may be related to Mark Ryan.